Since Dec.30th, I have been hearing an unusual signal at 14.320 MHz. 50 regularly-spaced long pulses, with rather rough audio modulation in two different audio tones. Tones alternate; 37 pulses in one tone, then 37 in the other. I have heard this signal on the West coast of the U.S.. Another ham on the East coast reports hearing it, too. The signal is heard intermittently, usually between 16:00 and 23:30 Universal Time. It is as strong as S. 7 to S. 9, at times. No identification that I can discern is ever given. Has anyone else heard this signal, and/or have any ideas about its source or identity?

Heard the unusual signal again today, intermittently, from about 20:35 to 21:30 U.T. Signal strength up to S. 5. Each long pulse could be heard to be broken up into 4 or five very rapid pulses. These were so rapid that their individual nature might be missed. Given normal 20 meter band propagation, the signal is not heard as early in the day as might be expected of a source to the East of my location. Further, it's not heard as late in the day as might be expected of a source to the West.

The pulsating signal on 14.320 MHz continues to be heard; intermittently, as before. It can not always be heard at the same hours, nor can it be heard every day. This obviously makes it difficult for some to take much interest in it, or even for the most patient and persistent observers to gather information on it. I find that it's now likelier for it to be heard between 23:30 and 01:15 Universal Time, than at the times previously noted. The signal has persisted for over 7 weeks. As more and more routine explanations for the signal are proposed, and then discarded as unworkable, the more mysterious this signal seems.

Just a guess... It may be some kind of local RFI. I get a pulsing sound when the neighbor runs her new washing machine. I also go a slightly different pulsing from my roommates plasma TV. I bought an ANC-4 (noise cancelling box) and that reduced much of it. That sounds like your problem too.

Also, you may have found CONTACT 2.

dave

Logged

First, make it work, then make it pretty.Yaesu Rigs: Kenwood TS-480HX, FT-8900R, FTM-350AR (Bluetooth motorcycle mobile), VX-8DR, SB-102 boat anchor (built one as a kid)

The pulsation rate of the signal is about 50 per minute (~ 0.8 Hz). It's audio modulated with about 500 and 1000 Hz sine waves, alternately in blocks of 37 pulses in each tone. The same signal has been heard on the same frequency in California, New England, Minnesota, and The Bahamas. It has never been heard on any other frequency. It fades in and out in just the same way as a distant transmission sometimes does. I found no 'hot spots' where the signal grows stronger, either in my house, yard, or areas nearest neighbors. I assumed it was an unusual signal mode from a non-ham transmitter intruding on 20 meters, but no one has been able to think of any known mode that sounds like this.

The fading would seem to be a dead giveaway that it's not local RFI. The fact that other locations nationwide can pick it up as well would tend to reinforce this, unless those other hams have neighbors with the same washing machine as Dave's neighbor.

Have you taken a look at one or more of the sites that have samples of various digital and utility signals? When you mentioned pulsating signal my first thought was OTHR, but that pulse rate would be really low for that.

Ideally, if you have the ability, get a screenshot of the waterfall display from one of the digital mode software packages showing the signal, and also grab a short recording of it. If you could post those it would probably help quite a bit.

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